The packaging of a variety of goods for transport and storage has always been a need for industrialized countries. While a wide variety of packaging techniques are available, of particular interest to industry is the packaging of products in small unit containers, such as metal cans. Here, the product to be packaged is placed in a container body, and a lid is then secured onto the container body to retain the product in the container and to prevent contamination of the product from the external environment.
Of particular interest to the industry and to the scope of the present invention is the metal container industry wherein a product is placed in a metallic container body onto which a lid is subsequently seamed. Such containers are often used in the food and beverage industry. Here, steel or aluminum lids are respectively seamed onto the top edge of a filled container. Typically, such lids may have pull tabs or other opening structures fabricated therein to allow easy manual opening of the container. Examples of such containers are aluminum beverage cans which predominant the packaging of beverages at the present time. Another example of such containers are those to hold liquid petroleum products, such as oil, engine additives, brake fluids, etc. Thus, it is typical to package liquid products in such containers.
A commonly used seaming apparatus utilizes a turret including a plurality of seaming stations. An unseamed container and a lid are placed in a seaming station, and a lid is engaged by a chuck which places a column load between the container body and the lid with the lid engaging the top peripheral edge of the container body. The chuck is connected to a gear drive which operates to rotate the container and lid. A first seaming roller engages the top edge of the container body and the outer peripheral edge of the lid with the first seaming roller and the chuck contoured to cooperate together thereby to change the shape of the lid and can edge as it is driven around the seaming station. Next, the first seaming roller is withdrawn, and a second seaming roller is toggled into position. The container continues to rotate in the seaming station to complete the seaming operation. Here, the peripheral edge of the lid and the top edge of the can are sequentially configured by the chuck acting with the first and second seaming rollers to form a final seam that typically hermetically seals the contents of the container from the external environment.
Existing seaming apparatus, however, are not without disadvantages. Usually, the structure of such a seaming apparatus is fairly complex, incorporating a large number of both stationary and moving parts. As a result of the large number of moving parts, a first problem relates to lubrication. Here, oil must be provided on a regular basis to reduce friction of the moving parts. The presence of oil in such quantities, though, is undesirable where the product to be packaged may become inadvertently contaminated with the lubricating fluid. Such is an especial disadvantage for the product packaged is a food or beverage for consumption.
Moreover, the use of a complex structure, including such structures as rotary tables, can lifters, the turret head chuck assemblies, the gear drives, knock-out rods, and the like require a typical can seamer to be a fairly expensive and massive structure. This is especially true where a sufficient number of seaming stations are provided to get a rapid throughput of containers during the seaming operation. The size and complexity of such machines increase their capital costs which make the cost prohibitive for small canners and packagers.
A further disadvantage, and one exacerbated by the complexity of such machinery, is that the malfunction of even one small part can result in substantial downtime of the seaming apparatus. Delays in the repair and maintenance of such machinery causes loss of production. This, along with the cost of the many parts, results in added overhead when such lid seamers are used in production operations.
In addition to the capital and overhead costs associated with the acquisition and maintenance of such machines, there is a further cost where a liquid product is to be packaged. Since the seaming stations are arranged in a circle, when a filled container is transferred to a seaming station, the substantial forces resulting from centripetal acceleration are present such that spillage of the product becomes problematic. Indeed, in beverage operations, it is not unusual to loose approximately three percent (3%) of the product to spillage during the seaming operation.
Due to the inherent design of such seamers, they exert a high column loading on the containers in order to maintain the containers upright and spinning with the lids pressed thereon during the seaming operation. However, such high column loading is undesirable with an increasing trend towards thinner walled aluminum containers that are employed to reduce material's cost. Such high column loading coupled with thin walled containers can result in undue compression and collapse of the container body during the seaming operation.
Accordingly, a need remains for improved seaming apparatus and methods to attach lids onto container bodies. There is a need for such apparatus to be lower in capitol costs as well as having lower costs of installation, maintenance and use. There are further needs to reduce product loss during, to allow seaming of thin walled containers and to provide more efficient seaming apparatus and methods which can be employed by small volume packagers.